In this study HMB was supplemented in a double-blinded, placebo-controlled, crossover design in 58 highly trained males.  To qualify the subjects had to have a minimum of 5 years training and a minimum of 4 sessions weekly in their sport discipline.  The authors concluded that HMB had advantageous changes in increasing fat free mass and reducing fat mass, while also improving indicators of aerobic metabolism such as VO2max, time to ventilatory threshold and power at ventilator threshold.